Phase III (Medication: 10 days), is a randomized, double-blind parallel design comparison of gabapentin vs. placebo on mechanisms of sleep. It is not a therapeutic or clinical trial. Phases II & III each have 7 days of monitoring sleep and activity, followed by 3 nights in the University of Michigan (UM) sleep laboratory to assess all-night EEG activity and Dim-Light Melatonin Onset (DLMO), a measure of circadian rhythm.